INTRODUCTION
Tree nut (TN) and peanut allergy prevalence has been increasing over the
last 20 years, particularly in pediatric age, as a presumable result of
changes in recent eating habits.1-3
Allergy prevalence for each TN appears to vary in different parts of the
world. A current systematic worldwide review of studies estimated the
global prevalence of probable TN allergy to range from 0.05% to 4.9%,
and peanut allergy between 0.5% and 2.5%.1,4,5
These food allergies can be potentially life-threatening, accounting for
a high number of fatal food-induced anaphylaxis, even when ingested in
very small quantities or inadvertently, as occult
allergens.1-3 Recent studies reported TN and peanut
allergies as the responsible for 70–90% of deaths from food-induced
anaphylaxis, with TN alone accounting for 18–40%.6
TN and peanut allergies usually develop early in life and tend to
persist into adulthood. According to previous published data,
acquisition of natural tolerance to TN and peanut occurs in only
9%–20% of allergic patients.7-9
The constant need for caution when choosing food and the potential risk
of anaphylaxis, frequently leading to diet and social activities
restrictions, significantly affects both patient and family’s quality of
life. Presently, and regardless of years of research, the management
cornerstone of these patients remains strict avoidance of the
incriminated nut, in addition to patient and family’s education on
prompt recognition of anaphylaxis and immediate use of
adrenaline.10,11 Other treatment possibilities have
been largely explored, namely oral immunotherapy, for peanut and TN
allergic patients, but their use is still limited.12
Homology amongst nut proteins and cross-reactivity between their main
allergens (namely 2S albumins, 7S and 11S globulins, lipid transport
proteins [LTPs], and PR-10) leads to frequent co-sensitization in
nut allergic patients, which does not always mean a true concurrent
allergy to different nuts.13 As a result, it can be
challenging to manage these patients and a distinction between
cross-sensitization and clinically relevant cross-reactivity between
different TN and peanut is critical, although it frequently requires
multiple oral food challenges (OFC) with the associated risk of a
possible anaphylaxis. For this fact, dietary restriction of all TN and
peanut is a common practice. Deeper knowledge of sensitization patterns
and investigation of possible anaphylaxis predictors would be of great
value to establish a more precise diagnostic approach and individual
dietary guidance for patients allergic to these
foods.1-5
In non-English-speaking countries, like Portugal, data on sensitization
patterns and anaphylaxis predictors is sparse. We aimed to characterize
a pediatric cohort with TN and peanut allergy followed in an
Immunoallergology department of a Portuguese tertiary hospital, and to
assess the utility of skin tests (ST), specific IgE (sIgE) and molecular
components (mcIgE), as well as ratio sIgE/total IgE in predicting the
anaphylaxis risk.